The Doctor:
Clara? You asked me what we're going to do. I told you: we're going to Hell. Or wherever it is where people die. If there is anywhere. Wherever it is, we're going to find Danny, and if it is in any way possible, we're going to bring him home.

Missy:
[about the Nethersphere]
Imagine you could upload dying minds to that, edit them, rearrange them, get rid of all those boring emotions, ready to be re-downloaded. Meanwhile, you upgrade the bodies. Upload the mind, upgrade the body. Cybermen, from cyberspace - Now why has no one ever thought about that before?